The field of this invention relates to bypass systems for downhole screens, particularly where the bypass systems have a variety of applications.
Downhole screens are frequently used to prevent solids from being produced from the formation. Typically, sand is delivered to the annular space around the screens in the well bore with the object being to fill up the annular space with sand or other materials generally referred to as xe2x80x9cgravel.xe2x80x9d Many times the delivered gravel can bridge, which results in bare spots around the screens and an ineffective gravel packing operation. Various types of systems have been developed in the past to address the inefficiency of the gravel delivery around an annular space in a screen downhole. Various solutions have approached the problem from the perspective of addition of various shunt tubes. Typical of these approaches are U.S. Pat. Nos. 5,417,284; 5,515,915; 4,945,991; 5,419,394; 5,341,880; 5,476,143; 5,113,935; and 5,082,052.
The apparatus and method of the present invention is intended to address some of the shortcomings found in the prior art solutions mentioned above. One problem that is encountered in making long shunt tubes that span a variety of joints is the ability to connect the shunt tube from one joint to the next while having the ability to make up each joint. Jumper lines to connect shunt tubes around tool joints presented an inefficiency in assembly of prior designs. One reference described above involved a pushed together design that was cumbersome and required clamping devices for each joint. Yet other designs used tubes with multiple perforations along their length, all of which are subject to clogging without being able to deliver the gravel along the length of the shunt tube as suggested in the references. Accordingly, one of the objectives of the present invention is to be able to use a technique with bypass tubes while at the same time allowing quick assembly to the proper amount of torque. Another objective of the present invention is to eliminate jumper lines around tool joints and to present a way of connecting the bypass tubes with the tool joints when the threaded connections in the tool joints are made up. Another objective of the present invention is to keep the bypass tubes isolated from gravel until they are ready to be used. Yet another objective of the present invention is to deploy a multiplicity of bypass tubes so that delivery of gravel can occur at multiple locations in a given zone. Yet another objective of the present invention is to stagger the availability of tubes on a bottom up order so that gravel can be deposited from the lower-most point to a higher-most point in sequence. Another objective of the present invention is to allow the bypass tubes to carry a signal or power transmitting devices such as fiber optic cable to obtain data from the well bore and transmit it to the surface. Those and other objectives of the present invention will readily apparent to those skilled in the art from a review of the preferred embodiment which appears below.
A system for preferable use in gravel packing is disclosed which includes a plurality of transport tubes which are mounted outside of gravel pack screens. The multiplicity of transport tubes cover a particular zone so that the tubes have a varying length to deposit gravel at different portions of the zone. The tops of the tubes are preferably sealed until ready for use and activated by applied pressure. In the preferred embodiment, rupture discs are found at the tops of each of the tubes, set for different pressures so as to open up the transport tubes to the lower most portion of a particular zone and later in sequence to the higher-most portion. The transport tubes are affixed to each section of pipe and are made up when two sections of pipe are made up to alignment marks. When the marks are aligned, the transport tube segments from each pipe section are in an aligned and sealed relation while the tool joint is properly torqued.